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Drinking Water FAQ

Frequently Asked Questions

General

Where does my drinking water come from?
The drinking water that is supplied to our homes comes from either surface water or ground water. Surface water collects in streams, rivers, lakes, and reservoirs. Ground water is water located below the ground where it collects in pores and spaces within rocks and in underground aquifers. We obtain ground water by drilling wells and pumping it to the surface.

Public water systems provide water from surface and ground water for public use. Water treatment systems are either government or privately-held facilities. Surface water systems withdraw water from the source, treat it, and deliver it to our homes. Ground water systems also withdraw and deliver water, but they do not always treat it. For more information on public water systems, visit CDC's Public Water Systems page. For more information on how public water systems treat water, visit CDC’s Water Treatment page.

A private well uses ground water as its water source. Owners of private wells and other individual water systems are responsible for ensuring that their water is safe from contaminants. For more information on private wells and individual water systems, visit CDC's Private Wells page.
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Public Water Systems

What type of health issues can be related to water quality?
The presence of certain contaminants in our water can lead to health issues, including gastrointestinal illness, reproductive problems, and neurological disorders. Infants, young children, pregnant women, the elderly, and immunocompromised persons may be especially at risk for becoming ill after drinking contaminated water. For example, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. Federal law requires that systems reduce certain contaminants to set levels, in order to protect human health.
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How do I know that the water in my home is safe to drink?
The United States Environmental Protection Agency (EPA) is responsible for making sure that public water supplies within the United States are safe. In 1974, Congress passed the Safe Drinking Water Act. This law sought to protect the nation’s public drinking water supply by giving EPA authority to set the standards for drinking water quality and oversee the states, localities, and water suppliers who implement those standards. In 1986 and 1996, the law was amended to protect drinking water and its sources, which include rivers, lakes, reservoirs, springs, and ground water wells.
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How do contaminants (germs and chemicals) get into my drinking water?
There can be many sources of contamination of our water systems. Here is a list of the most common sources of contaminants:
  • Naturally occurring chemicals and minerals (for example, arsenic, radon, uranium)
  • Local land use practices (fertilizers, pesticides, livestock, concentrated animal feeding operations)
  • Manufacturing processes
  • Sewer overflows
  • Malfunctioning wastewater treatment systems (for example, nearby septic systems)
Many contaminants that pose known human health risks are regulated by the United States Environmental Protection Agency (EPA). EPA makes sure that water meets certain standards, so you can be sure that high levels of contaminants are not in your water.
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Who do I need to contact to find out more information about water quality in my area?

Every community water supplier must provide an annual report, sometimes called a Consumer Confidence Report, or "CCR," to its customers. The report provides information on your local drinking water quality, including the water's source, contaminants found in the water, and how consumers can get involved in protecting drinking water.

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How often does our public water system test our drinking water?
Frequency of drinking water testing depends on the number of people served, the type of water source, and types of contaminants. Certain contaminants are tested for more frequently than others, as set forth by the Safe Drinking Water Act. You can find out about levels of regulated contaminants in your treated water for the preceding calendar year in your annual Consumer Confidence Report (CCR).

Learn more about your CCR and water quality in your area.

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What common contaminants are included in this testing?
The EPA sets standards and regulations for the presence and amount of over 90 different contaminants in public drinking water, including E.coli, Salmonella, and Cryptosporidium species. More information regarding the specific contaminants and maximum contaminant levels can be found on the EPA’s website (Drinking Water Contaminant Candidate List and Regulatory Determinations).
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What should I do if I want my household water tested?
The United States has one of the safest public water supplies in the world. However, if you are concerned about contaminants in your home’s water system, contact your state drinking water certification officer to obtain a list of certified laboratories in your state. Depending on how many contaminants you wish to test for, a water test can cost from $15 to hundreds of dollars. The Safe Drinking Water Hotline can give you information on testing methods.
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Who should I contact if my water has a funny smell, taste, or appearance?
A change in your water's taste, color, or smell is not necessarily a health concern. However, sometimes changes can be a sign of problems. If you notice a change in your water, call you public water system company.

If you want to test your water, your local health department should assist in explaining any tests that you need for various contaminants. If your local health department is not able to help you can contact a state certified laboratory to perform the test. To find a state certified laboratory in your area call the Safe Drinking Water Hotline at (800) 426-4791 or visit the State Certified Drinking Water Laboratories list.
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How can I find out if there has been a violation in our public water standard?
When water quality standards have not been met, your public water system must notify you through the media (television or radio), mail, or other means. Your annual Consumer Confidence Report (CCR) is another way to find out about the water quality in your area. It provides information regarding contaminants, possible health effects, and the water’s source.
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How do I find out if there is a boil water advisory or other water advisory in my community?
Your public water system is responsible for notifying residents if the water quality does not meet United States Environmental Protection Agency (EPA) or state standards or if there is a waterborne disease emergency. The EPA sets guidelines for when residents must be notified depending on the seriousness of a contamination event.

You should be notified by the media (TV, radio), mail, or other means. For more information, see CDC's boil water advisories page.

There are three levels of public notification. A Tier 1 notification pertains to the most serious and acute contamination events. Notification must be broadcast by local media within 24 hours. Tier 2 allows for a 30-day notification. Tier 3 provides notification through the annual Consumer Confidence Report (CCR).
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If there is a boil water advisory in my community, how do I disinfect my drinking water?
In order to disinfect your drinking water during a boil water advisory, you should boil your water at a rolling boil for at least one minute (at altitudes greater than 6,562 feet (> 2000 meters), boil water for 3 minutes). Boiling your water for at least one minute at a rolling boil will inactivate all harmful bacteria, parasites, and viruses from drinking water.

Chemicals (for example, bleach) are sometimes used for disinfecting small volumes of drinking water for household use. The parasite Cryptosporidium can survive a long time, even after the water is treated with chlorine or iodine. Cryptosporidium can be removed from water by filtering through a reverse osmosis filter, an "absolute one micron" filter, or a filter certified to remove Cryptosporidium under NSF International Standard #53 for either "cyst removal" or "cyst reduction." See A Guide to Water Filters. Filtering does not remove bacteria and viruses. Ultraviolet light treatment of water is not effective against Cryptosporidium at normally used levels.
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Wells

What are the main types of ground water wells?
There are three basic types of private drinking wells:
Proper well construction and continued maintenance are keys to the safety of your water supply. It is important to know what type of well you have. Well type affects how likely your water is to become contaminated and what kind of maintenance procedures you should follow. You may be able to determine the type of well you have by looking at the outer casing and cover of the well.
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As a private well owner, should I have my well tested?
Yes, as a private well owner, you are responsible for testing your well to ensure that your well water is safe to drink. The United States Environmental Protection Agency (EPA) is responsible for making sure that the public water supply within the United States is safe. However, the EPA does not monitor or treat private well drinking water. For information on testing your well water, visit Healthy Water's Well Testing page.
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How do contaminants (germs and chemicals) get into my well water?
A private well uses ground water as its water source. There are many sources of contamination of ground water. Here is a list of the most common sources of contaminants:
  • Naturally occurring chemicals and minerals (for example, arsenic, radon, uranium)
  • Local land use practices (fertilizers, pesticides, livestock, animal feeding operations, biosolids application)
  • Manufacturing processes
  • Sewer overflows
  • Malfunctioning wastewater treatment systems (for example, nearby septic systems)

The United States Environmental Protection Agency (EPA) does not regulate private wells. You are responsible for testing your well water and making sure it is safe.
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My well water has a funny smell or taste; should I worry about getting sick?
Any time you notice a significant change in your water quality, you should have it tested. A change in your water's taste, color, or smell is not necessarily a health concern. However, sometimes changes can be a sign of problems.
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What germs and chemicals should I test for in my well?
Several water quality indicators (WQIs) and contaminants that should be tested for in your water are listed below. A WQI test is a test that measures the presence and amount of certain germs in water. In most cases, WQIs do not cause sickness; however, they are easy to test for and their presence may indicate the presence of sewage and other disease-causing germs from human and/or animal feces. For more information on these contaminants and WQIs, please see the Healthy Water Well Testing page.

Water Quality Indicators:

  • Total Coliforms
  • Fecal Coliforms / Escherichia coli (E. coli)
  • pH

Contaminants:
  • Nitrate
  • Volatile Organic Compounds (VOCs)

Other germs or harmful chemicals that you should test for will depend on where your well is located on your property, which state you live in, and whether you live in an urban or rural area. These tests could include testing for lead, arsenic, mercury, radium, atrazine, and other pesticides. You should check with your local health or environmental department to find out if any of these contaminants are a problem in your region.

Please remember that if your test results say that there are germs or chemicals in your water, you should contact your local health or environmental department for help in interpreting the test, receive guidance on how to respond to the contamination, and test your water more often.
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When should I have my well tested?
You should have your well tested once each year for total coliform bacteria, nitrates, total dissolved solids, and pH levels. If you suspect other contaminants, you should test for those as well. However, spend time identifying potential problems as these tests can be expensive. You should also have your well tested if:
  • There are known problems with well water in your area
  • You have experienced problems near your well (i.e., flooding, land disturbances, and nearby waste disposal sites)
  • You replace or repair any part of your well system
  • You notice a change in water quality (i.e., taste, color, odor)
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Who should test my well?
State and local health or environmental departments often test for nitrates, total coliforms, fecal coliforms, volatile organic compounds, and pH (see above). Health or environmental departments, or county governments should also have a list of the state-certified (licensed) laboratories in your area that test for a variety of Water Quality Indicators (WQIs) and contaminants.

For more information, visit one of the links below or contact your local health department or the EPA Safe Drinking Water Hotline at (800) 426-4791.

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